In a drum brake system, a shoe is fixed at one end to a back plate via a pivot and the other end of the shoe contacts the piston of a wheel cylinder. Therefore, if the piston of the wheel cylinder pushes the shoe, the shoe shifts in relation to the pivot and presses against the inner circumference of the drum for producing a braking force.
Accordingly, in the conventional drum brake system, when the shoe compresses the drum, a portion of the shoe fixed via the pivot has a harder time contacting the inner circumference of the drum than a portion of the shoe that contacts with the piston of the wheel cylinder.